A manhole provides access to an underground passage or confined area through a manhole structure. The underground passage or confined area may contain public utility equipment, such as sewer lines, storm drains, electrical and telecommunication cables, etc. A manhole cover is a removable plate that forms a lid over the opening of a manhole. Manhole covers are used to prevent individuals and objects from falling into the manhole, as well as to prevent unauthorized access into the manhole.
In some installations, a surface (e.g., street, sidewalk, etc.) may be inclined relative to the manhole structure. In order to provide access to the manhole structure, a conventional floating manhole cover assembly includes a two-part structure with a lower frame attached to the manhole structure and a separate upper frame inserted inside the lower frame and “floating” in the lower frame, such that the upper frame may move relative to the lower frame.
In a conventional floating manhole cover assembly, the lower frame interacts with the ground surrounding the manhole structure and only a limited portion of the upper frame (e.g., the portion not inside the lower frame) interacts with the ground.